SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1b69b3383987d57863e0a0708ba8ef38155b540cb51cc37775129bb0876a7d83' 
  AND token = 'k2e57kf97WvifIcgWxCV+J5lgpm9CX37Y6uC37RBIxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}